Compound image-forming reflecting mirror optical system



Dec. 21, 1954 J. B. WALKER 2,697,379 COMPOUND IMAGE-FORMING REFLECTINGMIRROR OPTICAL SYSTEM Filed Sept. 16, 1953 2 Sheets-Sheet 1 FIG. I.

36 37 53 & 45 60 3 I 44 47 49 INVHVTOR.

JOSEPH B. WALKER BY 2: 6 4

AGENT Dec. 21, 1954 J. B. WALKER 2,697,379

COMPOUND IMAGE-FORMING REFLECTING MIRROR OPTICAL SYSTEM Filed Sept. 16,1953 2 Sheets-Sheet 2 FIG. 3. 7s

7 INVENTOR. 2 75 BY JOSEPH e. WALKER AGENT United States Patent COMPOUNDIMAGE-FORMING REFLECTING MIRROR OPTICAL SYSTEM Joseph B. Walker. LosAngeles, Calif. Application September 16, 1953, Serial No. 380,463

7 Claims. (Cl. 88-24) My invention relates to image-forming opticalsystems and particularly to those for combining images of two fields ofview.

In the arts of television, motion pictures and still photography it isoften desirable to combine scenes from two separate fields of view in amanner as to make it appear that these originated within a single fieldof view. An example is the apparent placement of actors amid sceneswhich may have been taken on travelogue photographic expeditions yearsbefore. Another is the combination of a commercial object either over orin an otherwise unrelated or at least physically separated scene. Suchprocesses are now of great practical importance in these fields, eitherresulting in large savings of time and money or in effects that couldnot otherwise be secured.

Other effects are desirable, but have heretofore been impossible witharrangements of the prior art. By manipulating an adjustment of mysystem it is possible to cause real people and a full-size station topull away as these would if viewed through a window in a train which wasleaving the station; everything involved in the operation beingstationary save the adjustment mentioned. This effect may be controlledat a distance and may increase in apparent speed, as a train wouldnormally accelerate out of a station. By manipulating two adjustments ofmy system the effect of take-off, landing or air travel can be produced.

Certain arrangements of the prior art have required that one of thescenes to be combined be upside-down in the taking of the motion pictureor television scene in order to appear rightside-up in the combinedview. This prohibits the combination of a glass containing a liquid orof a cigarette with smoke rising therefrom with a scene containing realpeople. My system can be arranged to allow these scenes to be properlycombined from all objects which are erect in fact.

Furthermore, it has previously been necessary to place the second(miniature) scene within optical arrangements so that actual physicaldifiiculties of manipulation and problems in lighting were encountered.In my system the optics is such that the second scene is outside theoptical system, comparatively speaking, and great latitude in lightingand composition of that scene is possible.

In optical combining arran ements two separate types are to berecognized; the additive and the mutually exclusive types. In theformer, the combined image light intensity is the sum of the individuallight intensities at any given point. In the latter, the combined imagelight intensity consists of the light intensity of either one image orof the other, but not of both. In the former arrangement one obiect issometimes seen through another object and in the latter arrangement anobject disappears if it moves into the space preem ted in the compositescene by the other field of view. These limitations are usually made ofno effect by care in production technique, but each arrangement isobviously limited.

In my system it is possible to operate according to either systemwithout modification of the apparatus and it is also possible to operateto any degree between the two systems, securing now effects or providinga greater range in allowable technique so that extended techniques ornear accidents, as may occur without recourse in live television, do notcause departures from reality.

- The versatility of my system stems from the use of reflective opticsrather than refractive, as has long been employed. How these aspects areattained will be set forth in detail hereinafter i An object of myinvention is to provide means for combining two fields of view into asingle image, indistinguishable as to its dual character.

Another object of my invention is to provide simple and easilymanipulable means for coherently simulating apparent motion of asceneeven though the nature of the scene makes genuine motion thereofimpossible.

Another object of my invention is to provide optical means for combiningtwo scenes in which both scenes may be outside the constricting confinesof the combining optical system.

Another object of my invention is to utilize reflective rather thanrefractive optics in an optical combining arrangement, therebyeliminating chromatic aberration and attaining manipulative advantages.

Another object of my invention is to provide means by which a real andessentially immovable scene may be framed and changed in apparentposition independently of a second scene and of the camera taking thecombined scene.

Another object of my invention is to provide an optical combining systemover which the camera may be panned, tilted and dollied, the combinedscenes acting as a single real scene.

Another object of my invention is to provide an optical combining systemin which the placement of each scene and the focus and magnification ofthe combined image may be electromechanically accomplished by control ata location remote from the system.

Another object of my invention is to provide an optical combining systemin which both scenes to be combined stand upright.

Other objects of my invention will become apparent upon reading thefollowing detailed specification and examining the related drawings, inwhich:

Fig. 1 shows a side elevation view of the essentials of my system,

Fig. 2 shows a side elevation view of an alternate embodiment of mysystem adapted for zoom lens operation and remote control,

Fig. 3 shows a plan view of an image-erecting embodiment of my system,and

Fig. 4 shows a side elevation of the embodiment of Fig. 3.

In Fig. l, numeral 1 indicates an object in the main field of view, suchas an actor. Concave mirrors 2 and 3, conveniently of first-surfaceglass construction, form a real inverted image 4 of object 1 in space asshown. Slightly further along the optical path a suitably illuminatedobject or picture 5 is located in an inverted position, a tree in thisexample. Lens 6 is the objective lens of the television, motion pictureor still camera 10. It forms a combined image consisting of the image 7of the actor and the image 8 of the tree on plane 9; the latter beingthe photosensitive electron-responsive surface of a television cameratube, an intermittently-progressed motion picture film, a still cameraplate or film, or the equivalent.

These essential elements are housed, positioned and adjusted as follows.Numeral 11 identifies the containing case for the mirror elements 2 and3 of my system. It has a reentrant tunnel portion 12 through which theoptical path from the main field of view passes to mirror 2. Thisprevents extraneous light entering the system. Mirror 2 is adjustable intwo dimensions. In Fig. 1 I have shown a manually operated support forthis adjustment. It consists of an inverted Y support 12 attached toknob 13, which gives control horizontally. Within that structure iscontained a flexible shaft 14 with a pinion engaging gear 15 and theopposite end of the shaft attached to knob 16, which gives verticalcontrol. These are the major controls for positioning the image of themain field of view in the composite image and for producing simulatedmotion of the first-mentioned image.

Mirror 3 is supported within the optically rigid case 11 upon theuniversal ball-and-socket joint structure 17. Adjustment screw 18 isattached to mirror 3 with an essentially ball-and-socket connection andis threaded 1nto case 11, so that rotation of the screw gives verticaladjustment to the mirror. In a similar fashion ad ustaudience is theresult. costing as much as onefthousand dollars per minute, versatilityof this nature is sought after. motion picture production, the high costof performers ment screw 19 gives horizontal adjustment of mirror 3.These adjustments allow modification of the position of the optical pathand the control of minor aberrations.

The optical path leaves the containing case at the lower right-handport-ion of it and through some degree of light block 20, included toprevent stray light from impinging upon mirrors 2 and 3. The object 5,of which the second element of the composite image is formed, issuputilized, of course, the primary purpose being to.illumi nate theside of object 5 which faces lens 6. Object 5 may be an actualthree-dimensional object, such as any .kind of miniature, an article'ofcommerce, a flower or other object held in the hand anddemonstrated; aswell as the picture of the tree shown which isa cut-out or is supportedon a transparent backing which occupies the remainder of the combinedimage area. Object 5 may also be a semi-transparent painting orrepresentation painted upon glass or other transparent support. In thisinstance, such portions of image 4 as lie behind the semi-transparentportions of 5 will be reproduced in the composite image at reducedintensity, .in amount corresponding to the opacity of the particulararea of 5 involved. The combined image will also be altered inappearance according to the relative brightness of the images 4 and 5and so rheostat 26 is included in the circuit to excite source 22,consisting of battery or electric power source 27 and switch 2%. Bysuitable adjustment of the rheostat the predominance of the scene 5 maybe varied, greater illumination thereof giving increased predominance,and by means of switch 28 the scene 5 may be included or essentiallyremoved from the composite image by providing .or withholdingillumination therefrom. The latter functioning occurs regardless of thenature of object 5. Without illumination and with an opaque object asilhouette thereof is obtained in the combined image.

Camera objective lens 6 is preferably of the mediumangle or mediumfocallength type and is adjusted in axial position to focus object 5 andsimultaneously image 4 upon the working surface 9. This is accomplishedby sliding the lens as required in the enclosing portion 29 of camerahousing 10, or by equivalent means.

How I achieve the objectives of combining two fields of view, and ofcombining these relatively free from the restrictive confines of anoptical system are now apthe composition of the scene represented byactor 1 in" the main field of view. in practical work.

In motion pictures and particularly in television a rehearsal usuallydetermines where actors and other movables in the scene such asbicycles, autos, .tea wagons and so on will be located. It is alsoaxiomatic in these arts that few performances come off exactly asrehearsed. It is too much to expect that performers who This is aserious disadvantage have lines to remember and things to do .will beable to occupy exactly their proper positions in the performance withoutlooking for marks on the floor in an obvious manner or otherwiseorienting or reorienting themselves for the requirement of properplacement.

. Such actions destroy the illusion of the play and .are

never tolerated. In nearly every situation a scene in television ispreviewed by the cameraman and/ or technical control personnel prior tothat camera taking over the program. if a simple finger-tip adjustmentis available, as my adjustments 13 and 16, the cameraman or a technicalassistantcan quickly make such readjustment as is required to give theconditions of the rehearsal and a PElfCCtlOIT Of presentation that isdiscernible 'to the With television programs now Similarly, in

This is not true with refractive optics, i. e.

and facilities pays a return to rapid manipulation, absent inotherprocesses where time is -much less valuable per unit. The utility, needand method of use of my device in the arts in which it may be used isnow apparent, as is the manner in which I achieve other of my statedobjectives.

Because the camera 10 in my system is physically separate from theremainder as shown in Fig. l and because an image of real object 5 andof real image 4 closely positioned thereto is formed therein it is seenthat the camera may be panned, tilted and dollied as desired and thecomposition of the composite image will remain a coherent Whole, thusaccomplishing another object of this invention.

1 have found that the position of image 4 is relatively the same whetherthe object It be far or near from my reflective optical system 2, 3within the ranges met in practice. If necessary, the position of object5 may be adjusted axially with respect to lens 6 so that image 4 andobject 5 are within the limits of the depth of focus of lens 6.

Fig.2 is an elevation view of my system utilizing my Electrazoom lens;This lens per'se has been described in my U. S. Patent .No. 2,532,685,dated December 5, 1950 in the motor operated .form in which I prefer touse it .here. It has been further described in my Patents 2,515,104.,July 11, v1950 and 2,547,187, April 3, 1951. In Fig. 2 the essentialoptical path and the same numgereci elements are the same as previouslyshown in .An important difference is electrical control of theorientation of mirror 2. This is accomplished by reversible motors 31and 32, which are each provided with .an internal gear train or worm andgear to give very .slow rotation to the working shaft in relation to thespeed of the armature. Motor 31 accomplishes horizontal change in theimage placement and motor 32 accomplishes vertical change. The threewires 33 emanating from motor 31 allow reversal of the direction ofrotation thereof when appropriately energized from a remote control andpower source not shown but well known in the art. The three wires 34 areequivalent to the above with respect to motor 32. The motors may be ofthe commutator or polyphase A. C. types. The remote point of control ispreferably the operating position of the technical director orequivalent technician in television operation or that of the cameramanor assistant cameraman in motion pictures. The television cameraman mayalso have control, the wires mentioned merely being extended totheproper operating position.

Another important difference is electrical control of the position ofthe second object 5. In Fig. 2 the case 11 .is afi'ixed to theElectrazoom lens and as a consequence to camera housing 35. In thefigure the relative size of case 11 and its contents has been enlargedfor clarity with respect to the Electrazoom lens and housing 35; thus,in practice, the whole structure may be unitary without awkwardness. Aslow motion motor 36 acting through pinion and rack provides focusbetween the .Electrazoom lens and the working surface 9 of the camera.Wires 50 take control of the motor to the operating location previouslydescribed.

Object 5 is mounted upon platform 37, which is constrained by guideportions of the main case bearing upon vertical sides 33 and'39. Side 38is provided with rack teeth 40, each tooth of which entends nearly allthe way horizontally of the side. Gear 41 engages this rack and isoperated by a slow motion motor behind it that is fastened to case 11.Wires 44 take control of the motor to the operating location previouslymentioned. Similarly, side 39 has vertical teeth 45 which engage gear46. This is operated by slow motion motor 47 which is fastened to case11 by bracket 48. Wires 49 take control of this motor to the operatinglocation.

It is seen that by suitable excitation of the motors mentioned object 5can be given any desired position transverse of the optical axis. Anydesired composition of the two fields of view can therefore beaccomplished by three means of adjustment. The general field of mainview in which object 1 is located may be selected by the cameraman bysuitably pointing camera 35, as is usual practice. Further placement ofthe image of that field of view can be controlled from the remotecontrol location by suitably exciting motors 31 and 32. The rela tionbetween images 7 and 8 on surface 9 may be determined by suitablyexciting motors 42 and 47 controlling the position of object 5. It willbe understood that the original pointing of the camera can be performedprior to the performance, or by a brief effort on the part of acameraman normally assigned to another camera, the composition of thecomposite scene being thereafter effected by a control location operatorjust prior to use.

Turning now to a description of how the Electrazoom lens is adapted tomy system, element 51 is the movable diverging lens and 52 is themovable converging lens of the Electrazoom. Lens 51 is translatedparallel to the optical axis by threaded worm 53 by reversible motor 54,which is actuated from the control location by means of wires 55. Lens52 is translated from lens 51 by cam 56 as has been explained in thepatents mentioned. Lens 57, normally converging and included in theElectrazoom in order to shorten the focal length, occupies the usualposition as shown. Lens 58 is a converging and movable one that I havefound desirable in adapting the Electrazoom to this system. Worm 53 isprovided with an extension having a thread 59 giving less travel perrevolution than that of the original worm. Internally threaded support60 imparts the motion to the lens. By the opposite hand of the thread ofsection 59 it is evident that the lens moves toward object 5 when lenses51 and 52 move together, an action that increases the magnification ofthe combination of the latter two. The movement of lens 58 accomplishesmaintenance of focus of images 7 and 8 on surface 9 of the camerautilizing the normal cam action of the Electrazoom lens. Without lens 58the cam action would have to be excessive because of the closeness ofimage 4 and object 5 to the Electrazoom.

With the embodiment of Fig. 2, therefore, it is not only possible toarrange composition of the combined image by remote control but it ispossible to zoom to a closeup and vice versa in a similar manner. Thismotor controlled embodiment of Fig. 2 is also superior for producingsimulated motion effects because of the smooth and uniform motion thatcan be attained in comparison to manual control.

The effect of the viewing audience being upon a train which is pullingout of a station is performed as follows. For object 5 a picture of thewindow frame with the Window portion cut out is used. This may includeadjacent details of the inside of the passenger car, if desired. Forobject 1 the necessary portion of a railroad station and real people areprovided. Such action of these performers as may take place while thetrain is stationary is carried on without excitation of any of the motorcontrols associated with the reflective optics of my system. When thetrain is to pull out of that station motor 31 is energized. For thispurpose it must be a variable speed motor; of which the A. C.-D. C.commutator universal type, the wound rotor synchronous locked-in systemof motion picture camera and sound recording type, and a motor with avariable speed cone-disk or equiva ent transmission are examples. Themotor is energized feebly at first, then at an accelerated pace to givethe impression of acceleration of the railroad train.

In a similar manner an elevator going either up or down can be simulatedbv accelerated excitation of motor 32 in the appropriate direction. Byexcitation of both motors 31 and 32 the impression of three dimensionalflight can be given. When combined with a zoom from a long shot to aclose up by exciting motor 54 a simulated landing of an aircraft can beaccomplished and bv reversed excitation, a takeoff. By utilizing apicture of an airplane for ob ect 5 it is possible to make it fly acrossa scene by excitation of motor 47 and to rise or fall by excitation ofmotor 42. Real objects of miniature size may be mounted upon platform 37in an inverted manner and thus constitute ob ect 5, as maytransparencies. slides and translucent, phosphorescent and self-luminousbodies.

I have found that the focal lengths of the mirrors 2 am. 3 are notcritical, nor is the spacing thereof. It is only necessary that thecombination form a real image approximately in the plane of object 5. Ihave shown two converging mirrors having concave surfaces and thesedifferent focal lengths; 14 and inches in one practical embodiment.These dimensions and the sum of them are subject to wide variations; onemirror may be plane or even convex as long as the other is of in creasedconcavity so that the combined focal length re mains within the norminallimits of the combined focal length required to form the image nearobject 5. Because of this flexibility I am able to minimize aberrations.It is also possible to form one or both of the mirrors 2 or 3 withaspheric surfaces to minimize aberrations. The cross-sectional curveshould tend toward the parabolic.

Finally, I have found that an obliquely positioned lens located upon theoptical axis in the position of lens 58 reduces spherical aberration. Itis for this reason that lens 58 is provided with an adjusting screw 61by which the obliquity to the axis may be adjusted. For mirrors 2 and 3one above the other a vertical tilt of lens 58 is required. With oneadjustment of mirror 3 with respect to the optical axis the top of lens58 is to be inclined toward object 5. With an opposite adjustment ofmirror 3 lens 58 is to be oppositely inclined. It is not necessary thatlens 58 move in order to accomplish this reduction in aberration; lens57 may be similarly adjusted by means of adjusting screw 62 or anotherpositive (converging) lens may be included in this region of the opticalsystem for this specific purpose. This method of correction may likewisebe applied to the optical system of Fig. l by merely including a lens ofthe nature of adjustable lens 57 of Fig. 2 in the optical path betweenobject 5 and lens 6. These lenses reduce principally sphericalaberration, regardless of axial position. Which direction lens 58 movesis determined by the focal lengths of the lenses involved.

Figs. 3 and 4 show an image-erecting embodiment of my system. Theprincipal mirrors 72 and 73 are similar to mirrors 2 and 3 of thepreceding figures, although of different inclination and, in general, oflonger focal length to correspond to a longer optical path. Mirror 72 isadjustably supported by elements 12 through 16 as has been described inconnection with Fig. 1. Mirror 73 is adjustably supported by previouslydescribed elements 17, 18 and 19, but with the latter two interchangedin position so that the mirror is inclined downward instead of upward,as was the case in Fig. l or 2. Light from the (actor) object 1 impingesupon mirror 72 in the same manner as upon mirror 2 previously. Mirror 72is further inclined from the vertical, however, and the bundle of raysnow pass downward at an angle of the order of 30 from the vertical andimpinge upon flat mirror 74, which lies essentially horizontally. Thismirror may be provided with adjustments as to inclination, as ball andsocket joint 75 and adusting screws 76 and 77, located to giveadjustment in two planes. From this mirror the light is reflected tomirror 73 and thence horizontally to another plane mirror 78, standingvertically and at an angle of to the optical path in plan as shown inFig. 3. This mirror may likewise be made adjustable, as by screws 79 and80. Located upon a convenient extension 81 of the enclosing housing 82is the object 5 (tree), this time positioned erectly. Object 5 issuitably illuminated by lamps and reflectors 83 through 86. Image 4 ofob ject 1 occurs in a plane close to that of object 5 and is erect. Thetwo additional reflections from mirrors 74 and 78 turn the image fromtop to bottom and side for side from that formed by the embodiments ofFigs. 1 and 2; mirror 74 accomplishing the former and mirror 78 thelatter.

The embodiment of Fig. 3 is shown with the simple objective lens 6 ofcamera 10 having focus-adjusting means 29 as first shown in Fig. 1.Images 7 and 8 of the objects 1 and 5 are formed as before on sensitivesurface 9, but this time inverted as occurs when a camera image isformed of a scene in nature under normal optical conditions. It isimportant to note that the prior image 4 of object 1 and object 5 areerect in this embodiment, thus a liquid may be contained in a glass,bubbles therein rise and smoke from a lighted cigarette or a chimney ina 1rlniniature rise normally, similarly, water flows down hi It will beevident to one skilled in the art that my em bodiment shown in Figs. 3and 4 may be modified to embrace the electromechanical automatic controlelements of Fig. 2 rather than the manual adjustments of Fig. l, andthat the Electrazoom lens may be employed instead of the simpleobjective 6. I have also found that the inclinations of all the mirrorsin my system, and particularly those of Figs. 3 and 4, may be alteredand still give the same or a desirably modified result. For instance,mirror 72 may be farther inclined from the vertical and mirror 74 raisedfrom the horizontal by adjusting screw 77. Mirrors 73 and 74 may beinterchanged in position and other changes .made in inclination,position and J'o'f curvature ofmirrors 72 and/or 73 may be increased andthat of the iflat mirror 74 decreased from infinity to "a finite value,as may mirror 73. Furthermore, mirror surface 74 may be made convex inshape and the radius 'of curvature of the other mirrors decreased. Inthis way :I am able to treat aberrations and second order effects .in aneifective manner.

In forming aspheric surfaces to control aberrations known methods oflocal grinding or of altering the thickness of the first-surfacereflective coating during vacuum deposit by attention to the placementof the evaporative .materialmay be employed. Also, second surfacemirrors with an anti-reflection coating on the first glass surface maybe employed and the thick lens formed by the intervening glass utilizedto control aberrations.

By means of altering the inclinations of the mirrors and the curvaturesthereof it is possible to change the physical form of my device, makingit higher and less wide, allowing an oval enclosing shape and so on. Themirror elements need not be round and/or rectangular as these have beenshown, but these shapes may be interchanged and oval shapes may beutilized to reduce the size of the device Without altering the opticalperformance thereof. It is only necessary that each mirror besufliciently large "to encompass the extent of the full optical cone atthe plane of that element, although additional mirror area :is desirablein order to accommodate shifts in the optical axis caused bymanipulation of the positioning adjustments. The optical axis has beenindicated by dashed arrow lines in the several figures, save Fig. 3,where these lines indicate the path of the principal ray originating atobject 1 which is to one side of optical center in this example of actorand tree utilized for illustration.

The mirrors of this compound optical system may be made of a metal suchas aluminum or equivalent. A suitable optical surface is obtained byworking the metal, by vacuum deposition thereon in addition, by platingor otherwise. Such mirrors provide a light-weight structure incomparison to that resulting when glass is used in such applicationswhere Weight is an important factor.

I have given numerical values for several dimensions and characteristicsof my system for the purpose of most distinctly teaching how it may beconstructed and used. Obviously, my invention is not limited to thesevalues nor to the proportions shown in the accompanying figures. l haveexplained how numerous variations are possible and this teaching willallow one skilled in the art to considerably depart from the embodimentsshown without the necessity of embarking upon further invention.

Having thus fully described my invention and how it.

practice in preferred forms is to be accomplished, I claim:

1. A compound optical system comprising an enclosure having openings, aconcave mirror positioned opposite one said opening to collect lightfrom a field of view containing objects defined by said opening, meansto adjust said mirror in elevation, means to adjust said mirror azimuth,a second mirror within said enclosure positioned nearer to said field ofview than said first mirror such that light from said field reflectedfrom said first mirror impinges upon said second mirror, means to adjustsaid second mirror in elevation and azimuth, said enclosure so formed asto allow said impinged light reflected from said second mirror to passthrough a second opening, said mirrors optically constituted to form areal image of the objects of said field of view beyond said secondopening, other objects in juxtaposition to said real image, plurallenses coaxially related to form a refractive optical system, saidsystem positioned to include said other objects and -=said real image inthe field of view thereof, an image receiving surface positionedoppositely of said system with respect to tie field of view thereof,means to alter the axial position of said lens system with respect tosaid surface to form a focused image of both said real image and. saidother objects upon said surface.

2. In combination in a compound optical system, reflective optics forforming a real image of an object, means for adjusting the inclinationof said optics for altering the position of said image, a second object,means for adjnstably positioning said second object adjacent to saidimage, a lens of adjustable focal length positioned to collectillumination from said second object and said image, a surface lying onthe'opposite side of said lensfrom said object and image and means foraltering the axial distance between said lens and said surface forsimultaneously focusing real images of both said object and image uponsaid surface.

3. A compound optical system comprising a mirror, electromechanicalmeans for altering the orientation of said mirror in two dimensions, asecond mirror positioned to receive light reflected from said firstmirror, said mirrors adapted to form a real image of an object, meansfor positioning a second object adjacent said real image,electromechanical means for altering the position of said second objectin two dimensions, a lens system positioned to collect light from bothsaid 'real image and said second object, a surface on the side of saidlens system opposite to said image and second object, electromechanicalmeans for altering the distance between said lens system and saidsurface to form an image of said image and second object upon saidsurface.

4. The system described in claim 3 in which the lens s stem is ofadjustable focal length and electromechanical means coactively connectedthereto to adjust the same.

5. A compound optical system comprising an enclosure having openings, aconcave mirror positioned opposite one said opening to collect lightfrom afield of view containing objects definedby said opening,electromechanical means for adjusting said mirror in a verticaldirection and other electromechanical means for adjusting said mirror ina horizontal direction, a second concave mirror within said enclosurepositioned nearer said field of view than said first mirror such thatlight from said field reflected from said first mirror impinges uponsaid second mirror, means to adjust said second mirror in twodimensions, said'enclosure so formed as to allow said impinged lightreflected from said second mirror to pass through a second openi g, saidmirrors optically constituted to form a real go of the objects of saidfield of view beyond said end opening, another object optically misciblewith real image, electromechanical means for changing the position ofsaid other object in two dimensions, means "for illuminating said otherobject, a converging lens itioned to include said real image and saidother object in the field of view thereof, means to adjust saidconverging lens oblique to the optical axis defined by said secondmirror and said lens, a variable magnification lens havplural lenselements positioned to collect the light vssed by said converging lens,electromechanical means for altering the focal length of said variablemagnification lens, said converging lens mechanically connected to saidmeans such that it is moved as the magnification said variablemagnification lens is increased, an image ei'ving surface positioned toreceive the light passed by said variable magnification lens,electromechanical means to alter the distance between said surface andsaid variable magnification lens to form an image of the field of viewof saidconverging lens upon said surface.

6. A compound optical system comprising a first concave mirror orientedto collect light from a field of view, a plane mirror positioned tointercept the light from said field of view reflected from said firstmirror, a second concave mirror positioned to intercept the light fromsaid field of view reflected from said plane mirror, a second planemirror positioned to intercept the light from said field of viewreflected from said second concave mirror, means to adjust the angularorientation of each of said mirrors, said system of mirrors formingerect real image of said field of view having the same sense side toside as said field, an object positioned near said image, means toilluminate said object, a lens system positioned to collect light fromboth said image and said object, means to adjust the axial position ofsaid lens system, and .a focal surface positionedwith respect to saidlens system to receive therefrom a single combined image of said realimage and said object.

7. A compound optical system comprising an enclosure having openings, aconcave mirror positioned opposite one said opening to collect lightfrom a field of view containing objects entering through said'opening,means for adjusting said mirror in vertical and horizontal directions, asecond mirror positioned below said concave mirror within said enclosuresuch that light from s d field reflected from said concave mirrorimpinges upon said second mirror, a third mirror positioned above andcloser to said field of view-within said enclosure than said secondmirror such that light from said field reflected from :said secondmirror impinges upon said third mirror and is refiected in a directionapproximately parallel to the light that passed from said field of viewto said concave mirror, a forth mirror positioned at an angle in thehorizontal plane with respect to said third mirror and so as to receivelight from said field reflected from said third mirror, said enclosureso formed as to allow said received light reflected by said fourthmirror to pass through a second opening, said mirrors opticallyconstituted to form an erect real image correctly sensed side to side ofsaid field of view, an erect other object positioned optically misciblewith said real image, means to illuminate said other object, aconverging lens positioned to receive light from both said real imageand said other object, a surface on the side of said lens opposite tosaid other object and means to alter the distance between said surfaceand said lens to focus an inverted image of said real image and saidother object upon said surface.

References Cited in the file of this patent 5 Number UNITED STATESPATENTS Name Date Saalburg Feb. 18, 1913 Newcomb Mar. 30, 1915 GarretteOct. 19, 1915 Morris Feb. 20, 1917 Roach Sept. 8, 1925 Curry Jan. 22,1929 Tolhurst Feb. 6, 1934 Seitz Nov. 23, 1943 Walker Dec. 5, 1950Oetjen Feb. 17, 1953

